Inghottse electric



C. LE 6. FORTESCUE.

SYSTEM OF DISTRIBUTION. APPLICATION FILED MAY 13, 1920.

3 SHEETS-SHEET l- J INVENTOR W I [bar/)" 16G Forfejcue Qfl/iw'zm KATTORNEY '0. LE 0. FORTESCUE.

SYSTEM OF DISTRIBUTION.

APPLICATION FILED MAY13, I920. Reissued NOV- 9, 1920. 14,978.

3 $HEETSSHEET 2.

WITNESSES: iNVENTOR' ATTORNEY C. LE G. FORTESCUE.

SYSTEM OF DlSTRlBUTlON.

APPLICATION FILED MAY 13, 1920.

Reissued Nov. 9, 1920. v

3 SHEET SSHEET 3.

, l INVENTOR Z7Mr/efZe0.Fhr/efcue BY WITNESSES:

ATTORNEY UNITED STATES "PATENT, OFFICE.

CHARLES LE G. FOBTESOUE, F PITTSBURGH, PENNSYLVANIA, ASSIGNOB; TO.WEST-INGHOUSE ELECTRIC & MANUFACTURING- COMPANY, A CORPORATION 'OF PENN- lliSYLVANIA.

SYSTEM OF DISTRIBUTION.

Specification of Reis'suedLetters Patent. l{eissued N 9 1920. 7 OriginalNo. 1,284,294, dated November 12, 1918, Serial No. 155,721, filed March19,1917.- Application for reissue filed ma 13, 1920. Serial No. 381,201.

T 0 all whom it may concern e it known that 1, CHARLES Ln G: FOR-TEscUE, a subject of the King of Great Brittions, irrespective of thevalue and character of the polyphase load, may bemain- '-tained inpolyphase circuits that are furnished with power from the single-phasecircuit through the above mentioned phasesplitting devices.

By means of my anced matica y maintained in the pol'yphase c1rcuits,irrespective of the values of the polyphase loads obtaining therein orthe rtivgler e present invention, balphase power-supply circuit may becontrolled at will or automatlcally maintained at any predeterminedvalue, irrespective of the load conditions obtaining in the polyphasecircuits. In consequence thereof,

,polyphase apparatus, such as I have indicated above, may beeconomically and efii- I ciently operated on a single-phase'powersupplycircuit with-results comparable to those obtained when operating onpolyphase circuits of the usual c aracter, Again, other loads may beconnected to the single-phase power-supply circuit and, by reason of thepower-factor control of the single-phase circuit obtained by the presentsystem, the single-phase circuit ma operate efliciently at. all timesalthough urnishing power to both polyphase loads and sinle-phase loadsof diverse char'acter. Thereore, the phase-splitting device of thepresolyphase conditions may be autoent invention, besides enablingpolyphase apparatus to operate from a single-phase supply circuit,serves as a power-factor control means for the single-phase circuit.

For a better understanding of the characteristic features of myinvention, refer-v ence may be had to the following descript10n and theaccompanying drawings in which igure 1 is a diagrammaticview of analternating-current distributing system em- .bodying one form, of myinvention; Fig. 2

is a diagrammaticview of a modified form of the control system embodiedin the system of Fig. 1; Fig. 3 is a diagram showing,

"in a simplifiedmanner, the circuit arrangements of a portion of thesystem of Fig. 1; Figs. 4 and 5 are vector diagrams illustratmg theelectrical conditions that obtain in the single-phase power-supplycircuit and the polyphase load 'circuits,under different conditions, ofthe system shown in Fig. 1, andFi-gs. .6 and 7 are vector diagramsillustratingthe electrical conditions that obtain in the sil'igle-phasepower-supply circuit and the polyphase load circuits-under differentconditions, of the system shown in Fig. 2.

'Referring to the system of Fig. 1, asingle-phase power-supply circuit,comprising 1 mains 1 and 2, is connected across an adjustable primarywinding 3 ofa power transformer 4. A secondary winding 5 of thetransformer lhas one of its terminals 6 connected to a group ofparallehconnected condensive elements 7 and a group of paral-Isl-connected adjustable inductive elements "8 through'leads 9 and 10,respectively. The

other terminal 11 of the secondary winding '5 is connected to a group ofparallel-connected condensive elements 12 and a group ofparallel-connected adjustable inductive elements 13 through leads 14 and15,'respec'-'- tively. The condensive elements 7 are severally providedwith brushes 16 that are adapted to slidingly engage conducting segments17 mounted on a control drum 18. The inductive elements 8 are likewiseprovided with brushes 19 that are adapted to slidingly' engage theconducting segments 5 17 of the control drum 18.

In a similar manner, the condensive elements 12 and the inductiveelements 13- are severally provided with brushes 20" and 21,respectively, which areadapted to slidingly engage conducting segments22- mounted on acontrol drum 23. The control drums 18 and 23 areseverally provided with wheel-and-worm mechanisms 24 that operate inunison by reason of the aforesaid worm elements being mounted upon acommon shaft 25 that, in turn,;is actuated by a motor 26.

Under normal conditions, condensive,ele-

I ments 7 are connected to the inductive elements 13 by means of aconductor 27' that simultaneously engages at least one of the conductingsegments 17 of the drum 18 and at least one of the conducting segments22 of the drum 23. Similarly, the condensive elements 12 are connectedto the inductive elements 8 by means of a conductor 28 thatsimultaneously engages at least one of the conducting segments 17 of thedrum 18 and at least one of the conducting segments 22 of the drum 23.

By referring to Fig. 3, it will'be'observed that the condensive elements7 of Fig. 1, which are represented in Fig. 3 by the single condenser 7,and the condensive elements 12 of Fig. 1, which are represented in Fig.3

-by the single condenser 12, alternate in position with the inductiveelements 8 and the inductive elements 13 of Fig. 1, which arerepresented, respectively, by single inducti've elements 8 and 13 ofFig.3 to form a closed circuit. that I will designate as a tuned bridgeor -.a phase-splitting device. Phase-splitting devices of a similarcharacter are disclosed in my copending applications Serial Nos. 83,748,filed Mar. 13, 1916, by Charles Le .G. Fortescue and assigned to theWestinghouse Elec. & Mfg. (10., and.

153,605, filed Mar. 9, 1917, by Charles Le G. Fortescue and assi ned tothe Westinghouse Electric & Mfg. ompany. The secondary winding 5 of thepower transformer 4 impresses the exciting voltage upon the. timedbridge and the voltage derived therefrom is impressed upon mains 29 and30 which are connected respectively to the conductors 27 and28.

An independent phase winding 31 of a polyphase load device 32 isconnected to the single-phase mains 1 and 2 through current coils 33 ofa differential power-factor relay 34 and a current coil 35 of adifl'erential .wattmeter relay 36. Another phase winding 37 of thepolyphase apparatus 32 has one of its terminals connected through acurrentcoil 38 of \the differential wattmeter relay 3% and current coils39 of thedifi erential power-factor relay 34 to the lead 30 which isconnected to the derived diagonal'of the phase-splitting device. Theother terminal of the derived phase winding 37 is connected, by means oftheconductor 29, to the other terminal. of the-derived diagonal of thephase-splitting device.

The differential wattmeter relay 36 comprises a voltage coil 40 which isassociated.

vmotor 26 in a given direction.

with the current coil 35 and connected directly across the independentphase winding'31 of the polyphase apparatus 32. A second voltage coil 41is associated with the current coil 38 and connected directly across thederived phase winding 37 of the poly- -phase apparatus 32. The relay 36is also provided with a rotatable arm 42 that is adapted to engageeither a contact member 43 or a contact member 44, depending upon whichwattmeter element of the relay exerts the predominating torque. Thedifl'erential wattmeter relay 36 is of a well known form of constructionand further explanation thereof is not deemed necessary. 1

The relay 36 is employed to control the excitation of an electromagneticreversing switch 45 which, in turn, controls the direc tion of rotationof the motor 26. When a circuit is established from the supply main 2,through a conductor 46, the conducting arm 42 of the relay 36,thecontact member 43 and a conductor 47, an electromagnet 48 of thereversing switch 45 is energized since one of its terminals ispermanently connected through leads 49 and'50 to the other supplymain 1. VVhen the electroma'gnet 48 is energized, a conducting arm 51 ofthe switch. 45 closes circuits through contact members 52 of said switch45 to rotate the When a circuit-is established from the main 2,

through the conductor 46, the conducting arm 42 of the relay 36, thecontact member 44 and a conductor 53, an electromagnet 54 of thereversing switch 45 is energized and the conducting arm 51 of the switch45 establishes circuits through conducting members 55, thereby causingthe motor 26 to rotate in the other direction.

' The motor '26, as'mentioned above, rotates the control drums ,18 and23 in the same direction and at the s ame-speed. Each of the drumscomprises two conducting segments that are spaced from each other andmounted 'on' the periphery of the drum.

When the drums are in their normal positions, as shown, the condnsiveelements of each group are connected'to the same conducting segmenteon'each drumand, likewise, the inductive elements of each group areconnected to the same conducting segment. For convenience only, thecondensive elements maybe considered as severally possessing the samecapacity and the inductive elements as severally possessing the sameinductance. The latter-are also provided with corresponding taps-sothat, at all times, the reactances afforded by them will be of equalvalue.

The inductive'elements and the condensive elements are capable ofbeingseverally connected either in the condensive arms or the inductivearms of the tuned bridge, depending upon the positions occupied by thecomtrol drums. When the drums are rotated in a clockwise direction, theconducting segments, normally in contact with all of the condensiveelements, are disengaged from some of the condensive elements andbrought into contact with some of the inductive elements. Thecondensive'admitta'nce of the bridge is thus decreased, since some ofthe inductive elements being connected in parallel with some of thecondensive elements, serve to increasethe reactance offered by thecondensive arms of the bridge. ,At the same time, the conductingsegments, normally in contact withall of-the inductive elements aredisengaged from some of the inductive elements and brought into contactwith some of the condensive elements. The inductive admittance of thebridge is also decreased,

since some of the condensive elements, be-.'

ing connected in parallel with some of the inductive elements, serve toincrease the reactance ofiered by the inductive arms of the bridge. Itis apparent that,,by rotating the drums in a counter-clockwisedirection, the condensive admittance of the bridge is decreased and,likewise, the inductive admittance of the bridge is decreased. The motor26, therefore, regulates the admittance of the several arms comprisingthe phase-splitting device. Whenthe control drums occupy the positionsshown in the system of Fig. 1, the admittances of the condensive andinductive arms of the bridge are at their maximum values.

The di fl'erential Power-factor relay 34 is ofv a usual type 0construction and comprises an upper group of voltage elements 58,mounted upon the shaft of the powerfactor relay 34, occupies a centralposition with respect to-two contact members 59 and 60. The power factorrelay 34, through the circuits established by the rotatable arm 58' andeither. the contact member 59 or the contact member 60, controls theexcitation of electromagnets 61 and 62 of a' reversing switch 63 of ausual type of construction.

I Thereversing switch 63, in turn,,controls the direction of rotation ofa motor 64 that controls, through a rack-and-pinion mechanism 65,the'position of an arm 66 upon which a plurality of adjustableconductors 67 are mounted; The conductors 67 severally' en agecorresponding tape on the inductive ehements '18 and 13 of thephase-splitting device. Since the adjustable conductors 67 are mountedupon thearm 66 and simultaneously engage corresponding taps on, theelements 8 and 13, the inductive reactances of the elements 8 and 13 areadjusted in unison, depending upon the direction of rotationof the motor64. From the foregoing, it will be apparent that the differentialpower-factor relay 34 also controls the value of the inductive reactanceofiered by the arms of the phase-splitting device, comprising the groupsof elements 8 and 13. In

other words, the. admittances of the induc tive arms of the bridge arealso controlled by the'relay 34.

As mentioned above, means are provided for controlling'the power-factorobtaining in the singlebase circuit under all load conditions. hepower-factor of the single phase circuit may be the result of either aleading current, a lagging current or a current directly in phase withthe single-phase voltage, depending upon the position of a rotatabledial 68 that is associated with a power-factor meter (not shown)provided With a conducting indicating arm 69. The conducting arm 69 ofthe power-factor meter registers upon a scale 70' that is fixed inposition and is calibrated to read the power factor of the single-phasecircuit. The dial 68 is provided with two spaced conducting segments 71and 72 with which the conduct- .ing arm 69 'is adapted to engage, undercertain circumstances. When the desired power-factor obtains in thesingle-phase circuit, the conducting arm 69 occupies a position mid-waybetween the conducting segments 71 and 72, and, under this circumstance,is out of electrical contact with them. If the dial 68 is rotated ineither direction in any convenient manner, the conducting arm 69, inorder to. occupy a position midway between the conducting segments 71and 72, must likewise rotate.

hen the arm 69 engages the conducting segment 71, a circuit isestablished from the main 2, through a conductor 73, a conductor 74,-the arm 69, the conducting segment 71, a lead 75, an electromagnet 76 ofa reversing switch 77, a lead 78 and the main 1. Similarly, when theconducting arm 69 engages the conducting segment 72, a circuit is es--tablished from'the main 2, through. the conductor 73, the conductor 74;the arm 69, the conducting segment 72, a conductor 79, an electrom'agnet8,0 of the reversing switch 7 7 theconductor, 78 and the main 1. It isobvious, therefore, that the excitation of the reversing switch 77,which is of a well known type of construction, is dependent upon whetherthe conducting segment 71 or the conducting segment 72 of the dial 68 isbrought into contact with the indicat-, ing arm 69 of the power-factormeter.

The reversing switch 77 in turn, controls the direction of rotation of amotor 81 that flctuates a rack-and-pinion mechanism 82 upon which anadjustable lead 83 is mounted. The lead 83 is connected, through anextensible conductor 84, to the main 2 and serves-to adjust the numberof active turns embodied in the primary winding 3 of the powertransformer 4.

The power factor of the single-phase cir-' cuit is, therefore,controlled by the position of the dial 68 with respect to the indicatingscale 70 of the power-factor meter. The dial, of course, may be soregulated as to control the power-factor obtaining in the single-phasesupply circuit, irrespective of any load conditions that may be imposedupon the supply circuit. It is obvious, of

' course, that unity power-factor may be maintained also in thesinge-phase circuit, if desired. r From the foregoing description, itwill be noted that the power-factor obtaining in the single-phasecircuit controls the value of the voltage to be impressed upon thephasesplitting device bythe secondar winding 5 of the power transformer4. ances' of the-inductive elements comprising the two inductive armsof! the phase-splitting device are controlled by the powerfactorsobtaining in the polyphase circuits and the ratio between the reactancesoffered by the inductive arms and the condensive arms of the bridge is,in this manner, va-

ried. .The admittances of all the bridge arms are controlled by thepower .demands in the polyphase circuits through the medium of therelay36'and the control drums In order to understand the operation of mysystem, attention is directed to-the' vector diagrams of Figs. 4 and 5in order that the electrical conditions simultaneously obtaining in thesingle-phase and pol phase circuits under different" load conditions maybe observed.

In .Fig. 4, a vector E represents the volta e impressed upon theindependent. phase winding 31 of the polyphase apparatus 32 1 by thesingle-phase circuit, and a vector E ssed upon the represents the voltae impIre derived phase win ing- 3 by the phasesplitting device. Thetwohase currents,

lagging behind their respective voltages E, and E, are represented byvectors I, and I.- In this particular instance, it isdesired to.maintain a resultant current in the singlephase circuit that leads theimpressed volta e b a predetermined phase angle a c direction of such avector representing.

the resultant single-phase current, therefore,

. maybe determined, since it is to be idvanced ahead of the voltagevector E by 1 Since the two xpolythe phaseangle a phase currents I; andI are equal, the value of the power component-of each of them may berepresented by a vector I which is in phase with the voltage vector EThe he reactwattless component of the vector I is represented by avector I,,. Since the power component of the single-phase resultantcurrent is .twice that of the. power component I of the vector 1 it maybe represented by a vector I I I'aving determined the power component ofthe resultant singlephase current to bed and knowing the in turn,furnishes current to the phase-splitting devioe. The current supplied tothe primary winding 3 may, therefore, be represented by a vector I' Thepower'component of the vector I' is equal to the power component of thevector 1,, and its wattless component is represented by a vector I whichmay be represented in the vector dia gram as; being a continuation ofthe vector that represents the wattless component of the vector 1,. v Itmay be mathematically demonstrated that the ratio of transformation ofthe tuned bridge or the ratio between the voltage impressed u on thebase-splitting device by 1 the secon ary win ing 50f the transformer 4and the voltage-derived therefrom, is equal to .the square-root of theratio between the wattless: component of the current sufpplied to theprimary winding 3 of the trans ormer 4', namely, the current I andthe-wattless component of the current supplied to the' independenthasewinding 31, namely, the current I... aving determined the values ofthese two wattless component currents,

as). mentioned above, and knowin the value of the derived IvoItageobtaine from the base-splitting device, namely, the voltage the valuefofthe voltage impressed u on the phase-splitting device may be ca culatedor arrived atfby .geometrical construction." I This ..voltage isrepresented ,by-a vector "E, which, in this instance,

is of all-relatively larger value than the voltage. E. J Knowing thevalues of the voltages impressed across the two diagonals of thephas'eesp litting device, which volta 681 are represented by the vectorsE and ,;,'.thevoltage impressed upon a conidensivqarm may be representedby a vector E; and that impressed upon an inductive "arm mayberepresented by a vector -E Knowing the directions, therefore, of thevoltage impressed upon the arms of. the bridge, the currents'severallyobtaining in these arms may be determined, since the currents aredlsplaced ninety degrees inphase from their respective voltages.Thevector I therefore, represents the current obtaining in one of theinductive'arms and the vector -1 represents the current obtaining in oneof the condensive arms. The cub rent vectors I and I, are, of course,components of the resultant current I obtaining in the bridge-fed orderived phase windin 37. r

The current supplied to the phase-splitting device bythe secondarywinding 5 of the power transformer 4: is likewise the resultant of thecurrents supplied to one of the inductive arms and one of the condensivearms and may be represented by a vector I which is in phase coincidencewith the vector 1... and has, as its components, the vector I and thevector I representing, respectively, the currents supplied to aninductive arm and a condensive arm of the bridge.

It will be observed that the currents obtaining in the polyphasecircuits, as Well as. their respective voltages, are in balancedtwo-phase relationship, the currents lagging in the same degree behindtheir respective voltages because ofthe inductive reactance of thepolyphase apparatus 32. The re: sultant current obtaining in thesingle-phase circuit leads the impressed voltage a predetermined phaseangle which it is desired to maintain constant under all load condi-.tions in the polyphase circuits.

The ratio of transformation of the transformer 4 maybe determined fromthe vec-,

. the currents obtaining in the polyphase circuits are increased and itis assumed that the angles of lag between their respective voltages aredecreased by reason of the improved power-factor at which the apparatus32 operates under increased loads. Corresponding vectors of Fig. 5: arerepresented by the same :reference characters employed in connectionwith the vectors of Fig. 3. It is not deemed necessary to explain, indetail, the construction of the vector diagram of Fig. 5, but it will beobservedthat the resultant single-phase current 1; leads the primaryvoltage E by the same phase angle that the resultant single-phase vectorI, of Fig. 4 leads .the impressed single-phase voltage. I

By comparing the two vector diagrams, it will be noted that the voltagevector E, of Fig. 5 is increased in: value, while the voltage vector Eis maintained at a constant value, As aconsequence, the ratio of Inorder to establish balanced polyphase conditions and maintain the samepower factor in the single-phase circuit under these changed loadconditions, the voltage impressed upon the phase-splitting device isvaried'automatically by means of the powerfactor-control element 68inserted in the single-phase circuit. Simultaneously therewith, thevalue of the inductive elements 8 and 13, embodied in thephase-splitting device and, consequently, the ratio of the admittancesof the bridge arms, by means of the difi'erential power-factor relay 34inserted in the polyphase circuits, are automatically va'ried. The ratiobetween the admittances of the inductive and condensive bridge arms, aswell as the value of the admittances of the several bridge arms, are"also varied automatically by means of the differential wattmeter relay36inserted in the polyphase circuits. Complete control of the system is,therefore, effected by the three aforementioned control elements thatseverally perform their independent adjusting functions to maintainthedesired conditions in the circuits. I

Although, for convenience, I have shown the inductive elements 8 and 13as adjust-I able, the condensive elements 7 and 12 may' be madeadjustable, while the inductive elements are maintained intact.

In Fig. 2, thecontrol systems are arranged to maintain balancedpolyphase conditions and a constant power-factor, preferably of onehundred per cent. in the single-phase circuit, under allload conditions.'In other words, the power-factor of the single-phase circuit is notcapable of being adjusted but must be maintained at a constantpredetermined value.

Assuming that the tuned bridge or phase splitting device is impressedwith a voltage equal to the derived voltage, the power transformer 4 ofFig;- l is dispensed with andthe reactive elements comprising the bridgeare directly connected to the supply mains 1 and 2 by means of theconductors 9 and 14. The bridge elements are similar, in all respects,to those of Fig. 1, the inductive elements being adjustable in order tovary the value of the reactance of the inductive elements, as well astheratio between the. admittances of the condensive and inductive arms ofthe b1'i( il'g 'e. control drums 18 and 23 are operated jby the motor 26the direction of rotation of which is controlled by the reversing switch45. The excitation of the reversing switch is controlled by means of thedifferential wattmeter relay '36 the elements of which are connected inthe polyphase circuits, as explained in connection with the system ofFig. 1. The reversing switch 77, which controls the .direction ofrotation of the motor 81 is, in this instance, controlled by meansof apower-fagtor relay 87, the current coils of which are connected incircuit with thesingle-phase main 1 and the voltage coils of which areconnected in shunt to the single-phase circuit through leads 88 and 89.

When the predetermined power factor obtains in the single-phase circuit,"at which power factor a rotatable arm 90 of the relay 87 occupies itsneutral position, the reversing switch 77 is denergized: and,conseuently, the motor 81 is inactive. Assume, for instance, that it. isdesired to maintain the power-factor of the single-phase circuit at. 100per cent. under all load condltion s. Whenever the power-factor variesfrom this value, the rotatable arm 90 will close a.cir-

cuit through one of the electromagnets of" the reversing switch 77,depending upon whether one of the contact members 91- and 92 of therelay is engaged by v the arm 90. When the reversing switch 77 isenergized,

the motor 81 is rotated in the proper 'direction to vary the value ofthe inductive elements comprising the phase-splitting device until thedesired power-factor is restored in the single-phase circuit.

To understand he operation of the system Y of Fig. 2, reference may behad to the vector diagrams of Figs. 6,,and 7. In 6, it is assumed thatthe polyphase motor 32 is operating under'a low load and, consequently,at a lbw power-factor. The currents obtaining in the independent phasewinding 31 and the derived phase winding 37 are represented,respectively, by vectors I and I. The voltage impressed upon theindependent phase winding 31 is represented by a vector E and thevoltage impressed upon the de-' rived phase winding 37 by a vector E.The,

voltage impressed upon one of the condensive arms is represented by avector E, and that impressed upon one of the inductive arms isrepresented by a vector --E,,. Since the tuned bridge or phase splitteris operating at a oneto-one voltage transformation, the dey ived.voltage. is equal to the voltage impressed upon the bridge. 4 I

The current flowing in the derived phase winding 37, which current isrepresented by a vector I, may be resolved into two components, namely,a. component-I which represents the current flowing through one i of thecondensive arms and a component I,

which represents the current flowing throu h one of the inductive armsof the bridge. The

current sup lied to the bridge is represented by a vector In, andthe'resultant single-phase current by a vector L. It will be observedthat thecurrentL is in phase with the vector E indicating that unitypower-factor obtains in the single-phase circuit. It will be observedthat the condensive admittance of the bridge is relatively large, asindicated by the current vector I,, while the inductive admittancefisrelatively low, as indicated by the current vector 1,.

. When the load upon the motor 32 is increased, the power-factors of thepolyphase circuits are likewise improved. These conditions arerepresented by the vector diagram of Fig. 7, where the referencecharacters of Fig. 6 are employedin connection with correspondingvectors It will be observedthat, in this instance, the vector Irepresenting the current flowing in one of the-inductive arms of thebridge, is greatly increased in value, while the vector 1,, representingthe current flowing in one of the condensive arms. of the bridge, isonly slightly increased in value. By comparing the length of the vectors1,. and ---I.3 of Fig.

7 with the corresponding vectors of Fig. 6,,

it will benoted that the vector I has increased several hundred percent. in value, while the vector I has increased a relatively smallpercent. only. This indicates that the inductive admittance of thebridge has increased considerably and at a much higher rate than thecondensive admittance,

under the increased load conditions inthe polyphase circuit.

From the foregoing description, it is ob-v vlous that, while a unitypower factqre zgists in the single-phase circuit, complete con trol isobtained for all load conditions, by varying the ratio between theadmittances of thebridge arms as well as varying the reactances ofthe-elements embodied in at least one pair of bridge arms possessinglike characteristics.

If the polyphase apparatus 32 operated at a constant power-factor,underiall load conditions, it would be unnecessary to vary theadmittances of the several arms, 1s to em- Complete control, in thisinstance,

ploy condensive elements the reactancesof which are severally equal toone another.

The reactances of the inductive elements are likewise maintained equalto one another.

As a consequence, the inductive elements and; condensive elements may beinterchanged between the bridge arms. by means of the embodiments of myinvention, it is to be understood that other modifications'may be madetherein and, consequently, that the invention is not to be limited tothe forms herein specifically described, since it is capable of otherembodiments that do not depart from the spirit and scope-of the appendedclaims. I

I claim as my invention: I 1. The combination with a'single-phasepower-supply circuit, polyphase load circuits, and phase-modifying meansconnected with said circuits to enable polyphase apparatus to operate'onthe single-phase. supply circuit, of automatic adjusting meansresponsive to varying power factor and load conditions 'in saidsingle-phase supply and said polyphase load for maintaining apower-factor of any predetermined value in the single-phase circuit andbalanced polyphase conditions inthe polyphase .circuits, irrespective ofthe values and characters of the polyphase loads.

r 2. The combination with a single-phase power-supply circuit, polyphaseload cirwits and phase-modifying means connected to said circuits toenable polyphase appara tus to operate on the single-phase supplycircuit, of automaticadjusting-means responsive to vary'ingpower-factorand load conditions in said singlephase supply and said polyphase loadfor controlling said phase-modifying means and for restoring the desiredphase relations in the polyphase circuits and the power-factor in thesingle.- phase circuit to a predetermined value, in case of departuretherefrom by reason of varying load conditions obtaining n the polyphasecircuits.

3. The combination with a single-phase power-supply circuit, polyphaseload circuits, and phase-modifying means connected to said circuits toenable polyphase apparatus to operate on the single-phase supplycircuit, of automatic adjusting means controlled by the power demands ofthe polyphase circuits, the power-factors obtaining therein and thepower-factor obtaining in the single-phase circuit for maintaining thedesired phase relations in the polyphase circuits and for maintaininga-constant powerfactor of any predetermined value in the singlehasecircuit.

4. T e combination with a sin le-phase power-supply circuit, polyphaseoad circuits, and phase-modifying means connected with said circuits toenable polyphase apparatus to oferate on the single-p ase supplycircuit, 0 the power demands in the several polyphase circuits, thepower-factors obtaining therein and the power-factor obtaining in thesingle-phase circuit, for .maintaining substantially balanced conditionsin the polyphase circuits and a power-factor of any predetermined valuein the single-phase circuit, irrespective'of the load conditionsobtaining in the polyphase circuits.

5. The combination with a single-phase powensupply circuit, andpolyphase load circuits, of a bridge comprising condensive and inductivereactance elements alternating in position with one another in a closedautomatic means controlled by circuit for interconnecting saidsingle-phase and said polyphase circuits, and automatic adjusting meansforp'maintaining a powerfactor 0 any predetermined value in thesingle-phase circuit and substantially balanced polyphase relations insaid polyphase load circuits irrespective of the varying power-factorsand varying loads which may exist in said polyphase load circuits.

6. The combination with a single-phase circuit, a polyphase circuit, anda hasespliting device comprising a plurality ofcondensiveand inductivereactance elements alternating in position with one'another'in aclosedcircuit for interconnecting said single-phase and poly-phasecircuits, one of the phases of said polyphase circuits constituting saidsingle-phase circuit and another phase being derived from saidphase-splitting device, of means for simultaneously varying ,the voltageimpressed upon -the phase-splitting device and the ratio between theadmittances of said elements comprlsing the phase-splitting device, inaccordance with the powerfactor obtaining in the' single-phase circuitand the load conditions obtaining in the; polyphase. circuits.

7. .The combination with .a single-phase power-supply circuit,polyphase, load cir'- cuits, and a phase-splitting bridge comprisingaplurality of arms having condensive and inductive characteristics andbeing connected in a closed circuit for permitting the interchange ofenergy between the singlephase circuit. and said polyphase circuits,

of, adjusting means responsive to varying power-factor and loadconditions in said single-phase supply and said polyphase load forseverally varying the admittances of said bridge arms and the ratiosbetween the condensive and inductive admittances of said phase-splittingbridge.

8. The combination with a single-phase power-supply circuit, polyphaseload cir cuits, and a phase-splitting bridge compris- -ing a pluralityof arms having condensive and inductive characteristms and beingconnected in a closed circuit for delivering energy from th'e..single'-phase circuit to said polyphase-circuits, of means for varying,the

adin'ittances of said bridge arms in accord-v ance with thedifierence ofloaddemands in the polyphaseload circuits. x

9. The combination with a single-phase power-supply circuit, 'polyphase'lo'ad circults, and a phase=splitting bridge comprising a plurality ofarms having condensive and inductive characteristics and being connectedin a closed circuit for delivering energy from the single-phase circuitto said polyphase circuits, of means for varying the admittances of thesaid bridge arms in accordance with the difference of load demands ofthepolyphase circuits, and additional means for varying the ratiobetween the condensive and inductive admittances of said phase-splitting'bridge.

10. A phase-splitting bridge comprising a plurality of arms havingcondensive char-.

acteristics and a plurality of arms alternattances of all of. the bridgearms.

11. A phase-splitting bridge comprising two arms having a plurality ofcbndensive elements and two arms alternating in position with. saidfirst arms and having a plurality of inductive elements, theelementspfat least one group of arms having the same for simultaneously varying,in'the' same d eby said phase-splitting device for rotating gree, theadmittances ofa-ll the arms possessing like characteristics,

12. A phase-splitting device comprising arms severally embodying aplurality of reactive elements, one of said arms possessing condensivecharacteristics and another of said arms possessinginductivecharacteristics, a control drum associated with said:

arms, conducting segments on said drum for normally connecting all ofthe elements constituting each arm in parallel relationship, and means,responsive to the power-factor and load demands of the currents suppliedsaid drum, whereby some of the elements normally positioned in one bfthe arms may binter'changed with some of the elements. normallypositioned. in the other of said "arms."

13. A phase-splitting bridge comprising two arms severally embodying aplurality v of. condensive elements-and two arms alter nati nginpositionwith said first arms and .severally'embodying a plurality ofinductive elements, control; drums that areseverally associatedjointlywith one condensive arm and one inductive arm, conducting segments onsaiddrums for normally connecting the elements embodied in thecondensive arms in parallel relationship and the elements normallyembodied in the inductivearms in' parallel relationship, and meansresponsive to the power-factor and load demands of the currents suppliedby saidrality of inductive*elements, of adjusting means responsive tothe power-factor and load demands of the currents supplied by saidphase-splitting device for correspondingly varying the admittances of atleast one group of arms possessing a-like characteristic and for varyingthe ratio between the admittances of the'arms pOSSessing likcharacteristics.

15. In a system of transmission, the combination with polyphasecircuits, of a phase-.

splitting bridge therefor comprising a network ofcondensive andinductive elements that is interconnected with a plurality of saidpolyphase circuits, said elements being so' arranged that the severalpolyphase electromotive forces are offered equal and electricallysymmetrical admittances.

16. A phase-splitting bridge comprising a. plurality of interconnectedreactive elements possessing diverse electrical characcharacteristicsbelng ad1ustable,"and means,

teristics, and independent means for ro ortionately varying theadmittances of said'ele a plurality of interconnected reactive elementspossessing diverse electrical characteristics, means for proportionatelyvarying.

- the admittances of said elements,an means for varyingthe ratiobetweenthe admittances.

19. A phase-splitting bridge comprising '12 a plurality of symmetricallyarranged ad justable reactive elements possessing diverse electricalcharacteristics, m eans for propor tionately varying the admittances ofsaid ele'.

ments, and independent means for'varying the admittance of at least onegroup of elepossess the same electrical charments that acteristics.

'20. A phase-splitting bridge comprising a plurality of elementsseverally having com 1 ments thereby maintaining the ratio be-' tweenthe admittances constant. 18. A phase-splitting bridge comprising.

' the admittances constant. v I 22. A phase-splitting bridge comprisinga plurality of elements severally having condensive and inductivecharacteristics and being connected alternatively ma closed c1r-' cuit,and independent means for simultaneously varying the admittanccsof two0'ppo-. sitely-positioned elements of said bridge.

phase-splitting bridge comprising a plurality of elements severallyhaving condensive and inductive 1 characteristics and being connectedalternately in aclosed circuit, and independent means for, proppr itionately varying the admittances of said elements thereby keeping theratio between densive and inductive characteristics and being connectedalternately in a. closed circuit, means ;for proportionately varying theadmittances of said elements, and means for varying the ratio betweenthe admittances. 23'. A phase splitting, bridge comprising a pluralityof elements having condensive and inductive characteristics and beingconnectedalt'ernately in a closed circuit, means for proportionatelyvarying the admittances of said '1 elements, and means for independentlyvarying the admittances of at least one group. of said elements thatpossess the same electrical characteristics.

.- In testimony whereof,' I have hereunto subscribedmyname this 10th dayof May,

' CHARLES LE e. FORTESOUE.

